ms1=400g
c1=10%; c1= md1x100/ms1
md1= 10x400/100= 4og
c2=md2x100/ms2
md2= 40x600/100=240g
md3= md1+md2= 280g
ms3= ms1+ms2=1000g
c3= 280x100/1000=..................calculeaza ; trebuie sa rezulte o valoare cuprinsa intre c1 si c2, indiferent de substanta !!!